Similar Freq, diff mode shapes

Using SimScale Solid Mechanics / FEA
1

prblm
prblm716Ă—616 6.09 KB
Modes

I have got equal frequencies in consecutive modes(as seen in the pic) , although the mode shapes are equal, but perpendicular to each other.

I would like to know what we can infer from this result?

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Hey @sgeorge!

Do you have a project link for us? And try to use a 2nd order mesh and tweak the mesh fineness a bit as this has at least to my knowledge tremendous effects on the results.

Best,

Jousef

1 Like
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More interestingly…which tool did you use?
I guess that’s not done with SimScale?

In general multiple mode shapes at the same frequency are perfectly fine and just a result of the symmetries in the model.

The fact that the modes of the same frequency are orthogonal tells you that there are basically infinitely many Eigenmodes spanning over a whole plane of possible modes with the exact same frequency but just rotated coordinate system.

Best,
Richard

4

Thanks. This was done with Nx CAE.

Its clear now that the results show similar modal frequencies and different mode shapes due to the symmetrical nature of the 1D beam element.